Method and apparatus for reducing spin-induced wafer charging

Abstract

A novel method and apparatus for reducing or eliminating electrostatic charging of wafers during a spin-dry step of wafer cleaning is disclosed. The method includes rinsing a wafer, typically by dispensing a cleaning liquid such as deionized water on the wafer while spinning the wafer; and spin-drying the wafer by sequentially rotating the wafer in opposite directions. The apparatus includes a wafer support platform that is capable of sequentially rotating a wafer in opposite directions to spin-dry the wafer.

1 . A method of reducing electrostatic charging of a wafer, comprising: 
 rinsing said wafer; and    drying said wafer by rotating said wafer in a first direction and rotating said wafer in a second direction.    
     
     
         2 . The method of  claim 1  wherein said rotating said wafer in a first direction comprises rotating said wafer in a counterclockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a clockwise direction.  
     
     
         3 . The method of  claim 1  wherein said rotating said wafer in a first direction and said rotating said wafer in a second direction comprises rotating said wafer at a rotational speed of from about 30 to about 5,000.  
     
     
         4 . The method of  claim 3  wherein said rotating said wafer in a first direction comprises rotating said wafer in a counterclockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a clockwise direction.  
     
     
         5 . The method of  claim 1  wherein said rotating said wafer in a first direction comprises rotating said wafer in a clockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a counterclockwise direction.  
     
     
         6 . The method of  claim 5  wherein said rotating said wafer in a first direction and said rotating said wafer in a second direction comprises rotating said wafer at a rotational speed of from about 30 to about 5,000.  
     
     
         7 . The method of  claim 1  wherein said rinsing said wafer comprises providing a cleaning liquid, rotating said wafer and spraying said cleaning liquid against said wafer.  
     
     
         8 . The method of  claim 7  wherein said rotating said wafer in a first direction comprises rotating said wafer in a counterclockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a clockwise direction.  
     
     
         9 . The method of  claim 7  wherein said rotating said wafer in a first direction and said rotating said wafer in a second direction comprises rotating said wafer at a rotational speed of from about 300 to about 5,000.  
     
     
         10 . The method of  claim 9  wherein said rotating said wafer in a first direction comprises rotating said wafer in a counterclockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a clockwise direction.  
     
     
         11 . The method of  claim 7  wherein said rotating said wafer in a first direction comprises rotating said wafer in a clockwise direction and said rotating said wafer in a second direction comprises rotating said wafer in a counterclockwise direction.  
     
     
         12 . The method of  claim 11  wherein said rotating said wafer in a first direction and said rotating said wafer in a second direction comprises rotating said wafer at a rotational speed of from about 200 to about 4,000.  
     
     
         13 . A method of reducing electrostatic charging of a wafer, comprising: 
 rinsing said wafer; and    drying said wafer by rotating said wafer in opposite directions in alternating order.    
     
     
         14 . The method of  claim 13  wherein said rotating said wafer in opposite directions in alternating order comprises rotating said wafer in a counterclockwise direction and rotating said wafer in a clockwise direction, respectively.  
     
     
         15 . The method of  claim 13  wherein said rotating said wafer in opposite directions in alternating order comprises rotating said wafer at a rotational speed of from about 30 to about 5,000.  
     
     
         16 . The method of  claim 15  wherein said rotating said wafer in opposite directions in alternating order comprises rotating said wafer in a counterclockwise direction and rotating said wafer in a clockwise direction, respectively.  
     
     
         17 . The method of  claim 13  wherein said rotating said wafer in opposite directions in alternating order comprises rotating said wafer in a clockwise direction and rotating said wafer in a counterclockwise direction, respectively.  
     
     
         18 . The method of  claim 17  wherein said rotating said wafer in opposite directions in alternating order comprises rotating said wafer at a rotational speed of from about 200 to about 4,000.  
     
     
         19 . An apparatus for spin-drying a wafer while preventing accumulation of electrostatic charges on the wafer, comprising: 
 a wafer platform for supporting the wafer; and    a motor operably connected to said wafer platform, said motor operable to selectively rotate said wafer platform in a counterclockwise direction and a clockwise direction.    
     
     
         20 . The apparatus of  claim 19  further comprising a controller operably connected to said motor for controlling rotation of said wafer platform.